1. Field of the Invention
The present invention relates to an endoscopic apparatus in which a diffraction grating is arranged on a transparent member such as a cover glass provided at the distal end of the endoscopic apparatus, and contamination on the transparent member is removed by applying ultrasonic vibration to the transparent member by means of a piezoelectric vibrator, thereby propagating a surface acoustic wave across the transparent member, and an operation control method for the same.
2. Description of the Related Art
When the distal end of an endoscopic apparatus (hereinafter, simply referred to as the distal end) is inserted into a body cavity during surgery, contamination such as body fluids or droplets produced by the use of an RF knife may adhere to a cover glass provided at the distal end. To remove this contamination, there are well-known techniques of imparting the vibrations of an ultrasonic vibrator to the cover glass to cause a surface acoustic wave to propagate. Such a technique is taught in Jpn. Pat. Appln. KOKAI Publication No. 2006-055275, for example, which discloses that a cover glass is provided at a distal end, and ultrasonic vibration is induced in the cover glass by imparting oscillations from an ultrasonic vibrator, thereby removing contamination from the cover glass.
In the technique of removing contamination from a cover glass by using a surface acoustic wave obtained by the application of ultrasonic vibration, an ultrasonic vibrator must be driven at high power in the range of several watts to several tens of watts. In a conventional endoscopic apparatus using a piezoelectric vibrator as the ultrasonic vibrator, high power is supplied to the piezoelectric vibrator without taking into account the driving state of the piezoelectric vibrator or the state of transmission of the surface acoustic wave.